PNG Suite from Willem van Schaik

This is (an older copy of) Willem van
Schaik's suite of PNG icons for testing PNG decoder
engines, PNG viewers, and PNG browsers. Most of the icons are 32x32,
and they run the gamut from 1-bit to 64-bit depth; grayscale, colormapped
and truecolor; interlaced or not; and with or without simple transparency,
full transparency (alpha channel), background chunks, histograms, gamma or
chromaticity data, comments, time stamps, and physical pixel dimensions. There
are even three invalid PNG images included, one 0x0 in size and the other two
corrupted by non-binary transfers.

Archives containing the full 2011 suite can be found on Willem's own,
multi-page
PngSuite site, which also includes GIF images for comparison.

Note that all images here are referenced with the standard HTML IMG
tag, not OBJECT or Netscape's EMBED; that means this page
will not display properly with any PNG plug-in due to bugs (er,
that is, limitations) in Netscape's plug-in architecture.
(This comment was relevant a decade ago...nowadays, never mind.)

version of this page with GIF images for comparison.
(Note that the gamma-correction PNG images will necessarily look somewhat
different from the corresponding GIF images unless your display
characteristics are similar to those of a NeXT.) Willem previously also
had an older, separate set of pages (using EMBED) for testing Netscape
and/or Internet Explorer PNG plug-ins.
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Alpha-channel images with and without background chunks:

The two rows should look identical in browsers that handle transparency
correctly. In a normal image viewer (one with no preferred background, i.e.,
not a web browser), the top four icons should have backgrounds
of yellow, white, gray and black, respectively; this will be visible on the
left sides of all four images and around the periphery of the first and third
icons (the two "X" images). The icons in the bottom row will generally
default to a black background in non-browser image viewers.

Histogram-chunk images:

Chromaticity-chunk images:

Images with different gamma chunks:

All six columns will look essentially identical (not counting the printed
numbers) if your browser does gamma correction. Within each icon, the two
rightmost bars (one solid color and one with alternating black and
max-intensity horizontal lines) will appear to be approximately the same
color, assuming your browser's gamma correction is correct for your
monitor. If your browser just dumps the raw pixel data on screen, the
icons to the left will have darker bars than those to the right.